How can I install Epson scan on a Mac running Mountain Lion (OS X 10.8) or Higher
Mountain Lion (OS X 10.8), Mavericks (OS X 10.9), Yosemite (OSX 10.10), El Capitan (OSX 10.11)
Mac OS X includes a security feature known as Gatekeeper. This means that any software that you install on your Mac will need to be verified by Apple. In the event that the software is not verified, your Mac will not allow it to be installed without user intervention. Older versions of Epson Scan are not verified by Apple so you will need to disable Gatekeeper in the operating system. To temporarily turn this feature off, carry out the following steps:
Click on the Apple menu and select System Preferences > Security and Privacy.
Click the General tab to change the Gatekeeper settings. Select the Anywhere option and click Allow From Anywhere.
Now install Epson Scan. After the installation has completed, ensure you return Gatekeeper to the previous settings.
Refer to the following Apple support article for further information: